One vertex per element, one color per generator, with an edge from x to x·s.
(1,2) involution — undirected(4,6)(7,8,12,15)(9,13,16,11)(10,14,20,22)(17,21,18,19)(24,26)(25,31)(30,34)(32,37)(9,16)(11,13)(17,18)(19,21)(23,24,28,26)(25,29,31,33)(27,34,35,30)(32,38,37,36)(3,4)(5,6)(7,9)(8,13)(10,18)(11,15)(12,16)(14,19)(17,20)(21,22)(23,25)(24,29)(26,33)(27,32)(28,31)(30,36)(34,38)(35,37) involution — undirected(7,10)(8,14)(9,17)(11,19)(12,20)(13,21)(15,22)(16,18)(23,26,28,24)(25,29,31,33)(27,34,35,30)(32,36,37,38)(7,11,12,13)(8,9,15,16)(10,19,20,21)(14,17,22,18)(23,27,28,35)(24,30,26,34)(25,32,31,37)(29,36,33,38)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.